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Message: <blockquote data-quote="brocknroller" data-source="post: 1271088" data-attributes="member: 665">I agree with Henry that the term "APO" has been bandied about with such indiscrimination that you need to be wary when you see it used in an optics ad.  However, I would not dismiss the use of ED/FL glass in birding binoculars as being unnecessary. I haven’t tried the FLs or Minox “APOs,” but I do see the value of ED glass in binoculars from a birding perspective. The Celestron 10x50 ED I owned showed me what no other binoculars I’ve had, including $1,000 10x42 LX L roofs and  premium 8x porros, could – a crow perched on a branch against a dull, gray winter’s sky with NO color fringing.  I thought my eyes were playing tricks on me. So I looked at the bird with my 8x32 SE and 10x42 LX L, and they both showed a false color halo around the bird, although the SE showed less than the LX L. The LX/LX L series shows excessive CA for their price points, IMO, particularly the 10x model. The Swift 8x44 ED I had “outshined” all my other binoculars on dim wintery days. The views were sharp and bright, and the colors were more vivid than my other binoculars (except my 8x32 LX, which on a sunny day showed colors almost as vivid, but it also showed a lot more color fringing in high contrast situations). I’ve also owned a Celestron 9.5x44 ED and a Swift Audubon 804 ED. Both exhibited these same beneficial characteristics (in fact, all except the 10x50 probably used the same 44mm ED element made by Vixen). When I first bought the 8x44 ED, it was raining out so I tried it in doors. My TV set has two small square buttons: one green, one red. The green is to show the TV is “ON” and the red shows if the station is broadcasting in stereo. With my other bins (8), when I focused on the clock on top of the TV and then focused the bins on the two squares, the green square was sharply focused while the red was out of focus. I could refocus the red square with the right diopter and get both colors in focus at the same time. When I did this same test with the 8x44 ED, both squares where in focus w/out diopter tweaking. That tells me that both wavelengths are hitting the same part of my retina. How could that not improve image quality? The bin might not throw a perfect airy disk, but it did show very vivid and bright color images and less color fringing in high contrast situations than my other binoculars. The 10x50 ED I did use for stargazing, and while I never did an airy disk test, I did test the color correction on Jupiter. Even near the horizon, Jupiter was a clean, round ball, with no color smearing. With the other 10x bin I had at the time, the 10x30 IS, Jupiter was a smear of colors, which got worse as the planet sun lower to the horizon. I realize that the planets are not the primary objects that stargazers view, but it illustrates my point about the noticeable, increased color correction with ED glass. Off-axis, the 10x50 ED did show CA, but very little on axis even in high contrast situations, which is when CA is most noticeable in binoculars. So if ED glass is so great, why I don’t I have any ED bins now? It takes more than ED glass to make a great bin.Each bin had its own issue: the 10x50 had a 5* FOV, fine for stargazing but too cramped for birding. Still, I do regret selling it at times when CA bothers me in my other binoculars; the 8x44 ED had too much pincushion, and the long 18 ft. close focus made it limited for birding; the 9.5x44 ED I bought was out of collimation and in poor condition so I returned it to the seller; the Audubon 8.5x44 804 ED was also in poor mechanical condition and had a very small sweet spot, returned that bin too.  Better samples of the 9.5xED and Audubon 804 ED would have been keepers. I think ED/FL glass is a welcome upgrade to birding optics especially in spotting scopes, but even for binoculars, it makes subtle but noticeable improvements that discriminating birders and optics aficionados would appreciate. However, taking the same roof, and adding ED glass to it, then charging hundreds of dollars more is a rip-off, IMO. Comparable configuration porros with ED glass only cost about $100 more than their non-ED porro counterparts. If Pentax and Minox want their roofs to compete with the Big Boys, they need to do more than just add ED glass and price their ED line in the premium bracket; they need to redesign their EPs to give their full sized binoculars a wider FOV while maintaining a wide sweet spot. Brock</blockquote>

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